Infectious SARS-CoV-2 Particles from Rectal Swab Samples from COVID-19 Patients in Brazil.

The main objective of this study was to investigate the dynamic of SARS-CoV-2 viral excretion in rectal swab (RS), saliva, and nasopharyngeal swab (NS) samples from symptomatic patients and asymptomatic contacts. In addition, in order to evaluate the replication potential of SARS-CoV-2 in the gastrointestinal (GI) tract and the excretion of infectious SARS-CoV-2 from feces, we investigated the presence of subgenomic nucleoprotein gene (N) mRNA (sgN) in RS samples and cytopathic effects in Vero cell culture. A prospective cohort study was performed to collect samples from symptomatic patients and contacts in Rio de Janeiro, Brazil, from May to October 2020. One hundred and seventy-six patients had samples collected at home visits and/or during the follow up, resulting in a total of 1633 RS, saliva, or NS samples. SARS-CoV-2 RNA was detected in 130 (73.9%) patients who had at least one sample that tested positive for SARS-CoV-2. The presence of replicating SARS-CoV-2 in RS samples, measured by the detection of sgN mRNA, was successfully achieved in 19.4% (6/31) of samples, whilst infectious SARS-CoV-2, measured by the generation of cytopathic effects in cell culture, was identified in only one RS sample. Although rare, our results demonstrated the replication capacity of SARS-CoV-2 in the GI tract, and infectious viruses in one RS sample. There is still a gap in the knowledge regarding SARS-CoV-2 fecal-oral transmission. Additional studies are warranted to investigate fecal or wastewater exposure as a risk factor for transmission in human populations.

Dermal extracellular matrix in cutaneous leprosy lesions

Thirty-eight biopsies of cutaneous lesions from leprosy patients [borderline tuberculoid (BT) 14, borderline lepromatous (BL) 18, lepromatous (LL) 6] were processed for staining of some extracellular matrix (ECM) components (collagen, proteoglycans, elastic fibers and fibronectin). Specific histological staining and the indirect immunofluorescence method with antibodies to collagen and fibronectin were utilized. The ECM of the normal dermis was strikingly modified in the inflammatory infiltrate. By Gomori's reticulin and anti-fibronectin immunostaining, replacement of the dense interlaced collagen fibers with a reticular mesh was observed in the infiltrate. The immunoreactivity obtained with anti-type I and anti-type III collagens showed positive fibrils and a lumpy pattern in the lepromatous and tuberculoid lesions with a higher amount in the lepromatous lesions. The lack of clear-cut boundaries between the normal dermis and the inflammatory infiltrate in the lepromatous (BL, LL) lesions was correlated with the blurred limits of the clinical lesions of this pole of the leprosy spectrum. Absence of elastic fibers in the infiltrate was a constant finding, and fuchsin-positive microfibrils were found in some infiltrates. The clear zone of lepromatous lesions was devoid of oxytalan fibers. Elaunin fiber rings around sweat gland acini were present even when the leprosy infiltrate was seen enveloping them. The original ECM is replaced by a newly assembled one, which is suited for the dynamic nature of the inflammatory process. The trophic effects of the ECM upon the cutaneous epithelial structures are modified so that atrophy and late degeneration ensues. These ECM modifications contribute, therefore, to the biological alterations of the skin functions in leprosy.